Analysis of wellbore stability characteristics of broken formations in Taxinan depression

ABSTRACT: Affected by the tectonic compression of Kunlun Mountains and Tianshan Mountains, fractured strata are widely developed in the southwest of the Pagoda, and the wellbore instability occurs frequently in the course of exploration. Based on the engineering geomechanical characteristics of fractured formation, combined with the data of pre-drilling prediction, measurement while drilling and post-drilling test, the characteristics of wellbore instability of fractured formation are analyzed, and the corresponding drilling fluid technical countermeasures are put forward. The research results show that the rock mass structure and mechanical properties of fractured formation are the main causes of wellbore instability in fractured formation. The optimization direction of technical countermeasures for fractured formation drilling fluid is determined as "how to improve formation strength (cement formation) and further strengthen plugging", and the technical countermeasures of "plugging + wall strengthening" in southwest Depression are initially proposed.